1. Field of the Invention
The present invention relates to on-machine-seamable industrial belts and methods of making industrial belts. Specifically, the present invention relates to seamed laminated belts for use in industrial applications.
2. Description of the Prior Art
Industrial belts referred to herein may include those used as conveyors and conveyor belts used in the food processing industries, belts used for the product of medium density fiberboard (MDF), and belts used in the production of nonwovens, i.e. carding, lapping, and other industrial applications. Typically these belts are impermeable which, for example, in the food processing industry is useful in preventing the adherence of bacteria and promotes ease of cleaning of the belt.
Traditionally, belts used in these industries or for these application have either been formed endless, by for example endless weaving, or alternatively a seam such as a clipper seam is attached to the two cross-machine (“CD”) edges of the belt in order to make the belt endless. Another approach which is sometimes used to form an endless belt is brazing or welding the cross-machine edges of the belt together. As will be readily appreciated, the brazing requires the belt to include metal portions that can be joined together. Yet a further approach for making a belt endless is the joining with a pin seam wherein the two CD-edges of the belt are made endless by interdigitation of loops formed from the machine direction (“MD”) yarns on the edges of the belt and inserting a pin or pintle there through to hold the interdigitated loops together.
The clipper seam mentioned above is a very common device used to seam a belt into an endless form. This variety of seam comprises a plurality of generally U-shaped clipper hooks, which are installed in an alternating relationship on the CD-edges of typically a corrugator belt, so that, when the two CD-edges of the belt are brought together, they may be interdigitated to define a passage through which a lacing cable or pintle may be directed to secure one edge to the other. The individual clipper hooks are of stiff metal wire, and have two parallel members which are separated from one another by an amount substantially equal to, or slightly less than, the thickness of the belt, and which have mutually directed barbs, so that, when pushed onto the edge of the belt, they are not readily removed. The two parallel members, which are on opposite sides of a CD-edge of the belt after the clipper hook has been installed, and which lie snugly against the opposite surfaces thereof, may be of equal or different length, and may therefor extend the same or different amounts longitudinally from the CD-edge of the belt.
Mechanical fasteners of other types are sometimes used. There are tapered overlays or joints for fastening or seaming, such as those used by Siegling GmbH, Hannover, Germany and Habasit AG, Basel, Switzerland on their belts.
Other seams may be sewn on which involves a woven web or spiral lace sewn onto both CD-edges of the belt with the woven web or spiral lace includes connecting loops. Alternatively, the woven base structure of the belt may contain connecting loops. In either event the connecting loops are meshed together to form the seam through the application of a pintle through the interdigitated loops.
However, these heretofore known methods of seaming have certain drawbacks for certain applications. One aspect of certain belts is the desire to ensure a smooth and uniform surface for the product being conveyed. One method of providing such a surface is for lamination of a layer or layers of material onto one another or onto, for example, a woven or knit base structure. However, the seaming methods described above do not always allow for a smooth surface. Those skilled in the art will appreciate that the seaming of laminated structure presents its own problems in terms of uniformity, impermeability, wear, and fatigue resistance.
One particular problem that affects laminated belts is that the lamination material, such as polyurethane or silicone films, may delaminate from the base structure. This delamination may often be caused by the method or the means employed for joining the two edges of the fabric.
This problem has proven to be particularly troubling in the lamination or coating of belts useful in the conveyance of foodstuffs. These coatings are often provided with certain useful attributes including antibacterial features or a particular resistance to adherence of the material deposited thereon. As can be imagined, the delamination of antibacterial coatings from a conveyor for food stuffs provides a two fold problem of contamination of the foodstuff by the delamination as well as a breakdown in the antibacterial effect. Accordingly, preventing this delamination is of great utility to the food processing and packaging industry.
Another issue is that since seaming methods do not address openings in the belt made by the seaming technique itself, such seams provide an opportunity for foodstuffs or contaminants to become imbedded in the seam and thereby nullify much of the antibacterial and cleanliness properties of the belt, that is otherwise impervious.
Obviously, there are ways to provide seamable fabrics for use in industrial applications, with the foregoing being set forth merely as examples. However, as with anything, there is always a desire to improve on or provide an alternative to what has been done previously. Seamable fabrics are no exception. The present invention is directed to resolving the shortcomings of the known seaming methods.